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[TenTec] 450 Ohm feedline

To: tentec@contesting.com
Subject: [TenTec] 450 Ohm feedline
From: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
Reply-to: tentec@contesting.com
Date: Thu, 15 Apr 2004 16:37:57 +0000
List-post: <mailto:tentec@contesting.com>
The purpose of twisting the line is not to reduce noise pickup and radiation, it is to help keep the line balanced.

I'd forget about using any kind of wood pane. Go with plexiglass. Just about any glass place will cut a plexiglass pane for you if you give them the measurements. Go to Radio Shack and get a pair of banana plug sockets/lugs and a pair of banana plugs. Drill two holes thru the plexiglass the width of the banana plug socket lug shafts and spaced the width of the feedline. Install them on the glass, bash out the old pane* (the fun part) and put in the plexiglass one, solder the ladder line on the inside to the lugs, solder the ouside end to the plugs. Now you have a feed through and quick disconnect. Mine handles 1200 watts no problem. Get a second pane made at the same time so if you ever move, you will be able to put a normal pane in the window.

Across the ground outside I have had good experience supporting the feed with pvc pipes stuck in the ground. And finally, as I've said before, I'd use a balanced feedline tuner such as the one from Palstar, just inside your window, and run coax from that to your shack. this works unless you qsy a lot, for that I'd consider a remote controlled tuner from John Bliss (Air and Water King--try a google search). This is if you want to run legal limit. For the Argo, you can probably just run the ladder line to an unbalanced tuner like the 238B at your operating position and that will work fine.

Rob Atkinson
K5UJ

*The way to safely bash out a pane is to tape an X across the pane with masking tape or duct tape, and smack the middle of the X with the handle end of a screwdriver on the X and hammering it with a hammer on the other end. Rubber mallet probably okay in lieu of the screwdriver/hammer.
The pane collapses outward but is held by the tape and the amount of glass falling is minimized. Of course if you aren't in a hurry (I always am) and don't want to have fun you can go around it chipping out the plaster : )


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